Marine steam-turbine.



G. G. CURTIS. MARINE STEAM TURBINE. APPLIUATION FILED MAY 15, 1911.

Patented May 28, 1912.

3 SHEETS- SHEET 1.

r P /n7/. Attorneys.

W i nesses C. G. CURTIS.

MARINE STEAM TURBINE.

211101111011 FILED MAY 15, 1911. -1 ,O27,698.

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j E i l 1 i l Witnesses: i 1

A 1 QQZW G. G. CURTIS. MARINE STEAM TURBINE. APPLIOATION FILED MAY 15,1911.

Patented May 28 1912.

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PATENT onricn MARINE STEAM-TURBINE.

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Specification of Letters Patent Patented May 28, 1912.

Application filed m 15, 1911.. Serial No. 627,113.

My inventlon relates to that arrangement :of marine steam turbines inwhich four propeller shafts are employed with two inde- 'endent powerequipments each distributed etween two or the shafts; and my object isto reduce for this purpose a construction an arrangement of turbineelements which will give a high eliiciency' and equal distributionofpower at both high and low power and in which the propeller thrust oneach shaft will be wholly or largely neutralized 'et ell substantialroads in accordance with the principles set forth in my applicationsSerial Numbers 593,159, 593,160 end 593,161, filed November 19, 1910. v

In the drawing Figure 1 is a plan view showingthe arrangement ofelements of the go-ahead and backing turbines on two shafts; Fig. 2 is elongitudinal vertical sec tion of the upper half of the high pressureelement of the go-eheud turbine. is a view'siinilzir to Fi -2 of theintermediate "pressure element 0 the go-ahesd turbine;

Fig. 4 is a similar view of the low ressu're element of the go-aheudturbine am of the low pressure element of the backing turbine; Fig. 5 isa similar View of thehigh pressure backing turbine; and Figs. 6 and 7are, re spectively, a radial longitudinal section on line w-q and adevelopment, of nozzles and vanes, s owing the use of guide passages toconserve the residual velocity in the wheel stages of the high pressureelement of the go-ahead turbine under cruising conditions. Referringparticularly to Fig. 11 A and B are the two propeller shafts, C, D, andE are respectively the high, ntermediate and low pressure elements ofthe .go head turbine, while F and G are respectively the high and lowpressure elements of the bucking turbine. The thrust collars 'on the.shafts A, B are shown at .7, 8. The pipes. 9 convey the steamfromtheboiler to the high pressure go-ahead element 0, pipes 10co'nnectO and D, and pipe 11 connects Dand E, these three elements taking thesteam in succession. The pipes 12 convey the boiler steam to thebacking-high pressure element F, and pipes 13 connect Fund G, which takethe steam in succession. The exhaust opening 14 is connected with thecondenser. The

high and low pressure go-ahead elements G, E, and the low pressurebacking element Gr aremounted on the shaftA, while the intermediatepressure go-ahead element D and the high pressure bucking element F aremounted on the shut't B. The steam pus sages or" the go-ahead elementsare so pro-' port-ioned that at full load the'elements C and E on theshaft A will develop SllbSl'zlIltially the some power as the element Don the shaft B, and likewise the hacking elements F and G are designedto develop substantielly the same power at full load The go-uhead highpressure element C (Fig. 2) is preferably composed of a nu1nber ofimpulse wheel stages, with partial peripheral steam admission, andhaving u plurality of velocity steps in each pressure stage. Forsimplicity of illustration, only the first and lost sets pt moving andstationury vanes in each stage are shown in Fig. 2, and this is alsotrueof all figures of "the drawing similar to Fig. 2. The moving vanesure as usual mounted on wheels or desire 15 carried by the shutt. thestationary vanes being carried. by the shell. The stages are separatedby diaphregnis 1.0 which carry 1 the nozzles, the first stage nozzlesopening" through the head of the shell in the steam chest 17. Valves 18and 18'(shown slide valves) Figs; 2 and 7, shut off sections of thenozzles of the several stages.

As shown in Fi s. 6 and 7, there pro;

vided between the lu st lrow ofmovingva-nes I of each stage and thenozzles of the suceeed ing stage a guide passage 19 composed. of top andbottom wells. sages direct the steam, discharged by" the vanesofeachistege into thenoiizle of the next stage andthereby conserve theresidiml yelocity. The guide passages are useful in improving theefiiciency at low or cruising speeds, since the vane velocity at lowspeed is not suilicient to abstract-the steam velocity, and hence it isonly necessary that these guide passages should be placed opposite thesections of the successive nozzles which are open zit-these speeds.

As shown-in Fig 7, the

are placed only'i'nthelinc of steam from the nozzle sections-whicliurenot "con osi These. guide pastrolled by valves, the other nozzleSections being close at cruising speed. The turbine element C beingpreferably composed wholly of wine elements havin no difference inpressure on the opposite sides of the wheels, there is no axial thrustin this element ex cept such as may be produced by differences in shaftareas (if any) at the opposite ends of the element. The balancing of thepropeller thrust is provided for by the construction of the low ressureelement E on the same shaft which will be presently described.

The go-ahead intermediate pressure element- D ig. 3) is preferablyprovided with an initial wheel stage having velocity steps, but thiswheel stage may be omitted. The nozzle sections for this wheel stage 20(when used) are controlled by valves 21 similar to the valves 18 and 18.Following the wheel stage 20 is a drum stage 22, having preferably anumber of single velocitystep impulse, pressure stages, .wlth completeperipheral steam admission. The drum of the drum stage 22 is connectedwith the shaft by a steam-tight pressure head 23 v which carries thedifference in pressure produc'ed by all the pressure stages on the drumand gives a thrust opposed to the propeller thrust on the shaft B.Following the direct drum stage 22 is a reversed drum stage 24 havingpreferably a number of single velocity-step impulse, pressure stages,with complete peripheral steam admission, and con nected with the shaftby a steam-tight pressure head 25 which is subject to the diiference inpressure produced by all the pressure stages on the drum and exerts anaxial thrust in the same direction as the propeller thrust. The two drumstages are separated by a diaphragm. 26 supported by the shell,

and pipes 27 connected with the shell forward of this diaphragm andextending to the rear end of the shell, carrying the steam from thedirect drum stageto the reversed drum stage. The steam passages are sopro portioned that, taking into consideration the axial thrusts producedby the shaft,- thrust 1 areas, the thrust produced by the head 23 of thedirect drum'stage will be enough greater than the thrust produced by thehead 25 of the reversed drum stage to practically neutralize thepropeller thrust at all substantial loads, as explained in my applications referred to. a

The go-ahead low pressure element E (Fig. 4) is composed of a singledirect d1 um stage 28 having preferably a number of single velocity-stepimpulse, pressure stages, with complete peripheral admission, the ,drumbeing connected to the shaft by a steam-tight pressure head 29. Thisressure head gives an axial thrustwhich, ta ring into consideration thethrusts produced by the shaft thrust areas, practically neutralizes thepropeller thrust on the shaft A at all substantial loads. No reversedrum stage is necessary because the steam pressure is lowered to such apoint when it reaches the element E that a single pressure head ofsuitable area will give the desired result.

As has already been stated, the steampassages of the three go-aheadturbine elements are so proportioned that at full load the high and lowpressure elements on one shaft will. develop substantially the 'samepower as the'intermediate pressure element on the other shaft. The fullpower condition is secured when all the stage-valves are open. Byclosing the stage valves in the high pressure element, the greatpressure drop which would take place in this element when the steam flowis reduced at cruising power, if all the nozzles are left open, can

be prevented. I have found that by a proper adjustment of these valvesthe pressure distribution in the three go-ahead elements can be madesuch that substantially equal power will be developed on the two shaftsat cruising power. The use of a wheel stage and nozzle valves in theintermediate pressure element also aids in securing this result,although an approximationto the result can be secured without thisfeature.

The high pressure backing element F on the shaft B (Fig. 5) is composedof two or more partial admission wheel stages 30 and a completeadmission drum stage 31, while the lowpressure backing element G on theshaft A (Fig. 4) is composed of out! or more partial admission wheelstages 32 and a complete admission drum stage 33. The element F has aseparate shell, while the element G, may be inclosed in a continuation,of the shell of the go-ahead element The dri'ims of the backingelements areconnected with the shafts by steam-tight ressure heads 34,35,which produce axial t rusts opposed to the thrusts of the propellersin backing.

The drums of the several go-ahead and backing elements, instead ofoperating on the impulse principle may be provided with vanes operatingon the reaction principle, in

which case the axial thrusts produced by the differences in pressure onthe rotating vanes would be taken into consideration in making provisionfor neutralizing the propeller thrust; and it should also be understoodthat, in respect to certain features of the invention hereinafter.claimed, and except where otherwise indicated by the language orsubject-matter of the claims, the high pressure, go-ahead element may bea reaction element,

on'one shaft and an intermediatepressure turbine element on the othershaft, thelat- 'ter having reversed drum stages, substantially as setforth. a

. 2. In a marine steam turbine, the combinationwith two propellershafts, of high and low pressure turbine elements on one shaft and anintermediate pressureturbine element on the other shaft, the latterhaving reversed drum set forth. I

3. In a marine steam turbine, the combination with two propeller shafts,of a prime stages, substantially as mover and a .low pressure turbineelement on one shaft and an intermediate pressure turbine element on theother shaft, the intermediate pressure turbine element having reverseddrum stages and adapted to develop at full power substantially "the samepower as the combined power of the power eleinenitls on the first shaft,substantially as set 'ort r 4.. In a marine steam turbine,the-combination with two propeller shafts, of high and low pressureturbine elements on one shaft and an intermediate pressure turbineelement on the 'othershaft, the latter having reversed drum stagesandadapted to develop at full power substantially the same power as thecombined power of the high and low pressure elements on the first shaft,substantially as set forth.

5. In a marine steam turbine, the combination with two propeller shafts,of high and ,low pressure turbine elements on one shaft, means forproducing an axial steam 7. In a marine steam turbine, the conibi nationwith two propeller shafts, of an intermediate pressure turbine elementon one shaft, a high pressure 'turbineelement on the other shaftcomposed of wheel impulse stages separated by diaphragms, and a lowpressure turbine element on the same shaft as the high pressure elementand composed of a single drum stage opposing the propeller thrust,siibstantlally asset forth.

8. In a marine steam turbine, the combination with two pro ller shafts,of high and low pressure tu-r ine elements on one shaft composed.respectively of wheel im pulse stages, and a single drum'stage, thelatter opposing the propeller thrust, and an intermediate pressureelement on the other shaft having reversed drum stagesv producing aresultant thrust opposed to the propeller. thrust, substantially as setforth.

9. In a marine steam turbine, the combination with two propeller shafts,of high and low ressure turbine elements on one shaft, an intermediatepressure turbine element on the other shaft, such elements beingproportioned to produce substantially equal power on'the two shafts atfull powe and means controlling the pressure dlstrlbution at cruisingpower 1n each of the several turbine elements so that substantiallyequalpower is developed on the two shafts at cruising power,substantially as setforth.

10. In a marine steam turbine, the combination with twoj: :1 moreimpulse wheel stages, of stage nola'zle" valves for each stage,controlling part of the nozzles, cruising nozzles not controlled by thestage valves, and guide passages between the moving blades of each stageand the cruising nozzles of the next stage to \';onserve the residualvelocity at cruising speeds, substantially as set forth.

11. In a marinesteam turbine,the combination with two propeller shafts,of two backing turbine elements mounted on the respective shafts andtaking the steam flow in succession, the high pressure backing elementhaving one, or more wheel impulse stages and a drum stage opposing thepropeller thrust and the low pressure backing element having a drumstage opposin the propeller thrust, substantially as set orth.

12: In a marine steam turbine, the combination with two propellershafts, of two backing turbine elements mounted on the respective shaftsand taking the steam flow in succession, each of such backing turbineelements having .one 'or more wheel impulse stages and a drum stageopposing the propeller thrust, substantially as set forth.

This specification signed and witnessed this twelfth day of May, 1911.

CHARLES G. CURTIS.

Witnesses J on L. Loreen, RUDOLPH J. GUs'rArsoN.

